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Investments (Details 7) (USD $) In Millions	3 Months Ended		9 Months Ended
Investments (Details 7) (USD $) In Millions	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Investments
Net unrealized gains related to changes in valuation of fixed income securities subsequent to impairment measurement date	$ 211		$ 211		$ 322
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(450)		(450)		(615)
Credit Losses on Fixed Income Securities
Balance	(912)	(1,309)	(1,046)	(1,187)
Cumulative effect of change in accounting principle		81		81
Additional credit loss for securities previously other-than-temporarily impaired	(56)	(101)	(133)	(265)
Additional credit loss for securities not previously other-than-temporarily impaired	(25)	(9)	(82)	(197)
Reduction in credit loss for securities disposed or collected	66	104	313	330
Reduction in credit loss for securities the Company has made the decision to sell or more likely than not will be required to sell		42	15	43
Change in credit loss due to accretion of increase in cash flows	4	1	10	4
Balance	(923)	(1,191)	(923)	(1,191)
Municipal
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(12)		(12)		(27)
Corporate
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(36)		(36)		(31)
Residential mortgage-backed securities ("RMBS")
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(372)		(372)		(467)
Commercial mortgage-backed securities ("CMBS")
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(8)		(8)		(49)
Asset-backed securities ("ABS")
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	$ (22)		$ (22)		$ (41)